/**
 * Copyright (c) 2005-2011 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: Fixtures.java 1593 2011-05-11 10:37:12Z calvinxiu $
 */
package com.se7en.core.mapper;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.beanutils.PropertyUtils;
import org.apache.commons.lang.StringUtils;

import com.se7en.core.utils.ReflectionUtils;

/**
 * 提出集合中的元素对象的属性(通过Getter函数),组合成新的集合.
 * 
 * @author calvin
 */
@SuppressWarnings("unchecked")
public class CollectionMapper {

    /**
     * 提取集合中的对象的属性(通过Getter函数), 组合成Map.
     * 
     * @param collection
     *            来源集合.
     * @param keyPropertyName
     *            要提取为Map中的Key值的属性名.
     * @param valuePropertyName
     *            要提取为Map中的Value值的属性名.
     */
    public static Map extractToMap(final Collection collection, final String keyPropertyName,
            final String valuePropertyName) {
        Map map = new HashMap();

        try {
            for (Object obj : collection) {
                map.put(PropertyUtils.getProperty(obj, keyPropertyName), PropertyUtils.getProperty(obj,
                        valuePropertyName));
            }
        } catch (Exception e) {
            throw ReflectionUtils.convertReflectionExceptionToUnchecked(e);
        }

        return map;
    }

    /**
     * 提取集合中的对象的属性(通过Getter函数), 组合成List.
     * 
     * @param collection
     *            来源集合.
     * @param propertyName
     *            要提取的属性名.
     */
    public static List extractToList(final Collection collection, final String propertyName) {
        List list = new ArrayList();

        try {
            for (Object obj : collection) {
                list.add(PropertyUtils.getProperty(obj, propertyName));
            }
        } catch (Exception e) {
            throw ReflectionUtils.convertReflectionExceptionToUnchecked(e);
        }

        return list;
    }

    /**
     * 提取集合中的对象的属性(通过Getter函数), 组合成由分割符分隔的字符串.
     * 
     * @param collection
     *            来源集合.
     * @param propertyName
     *            要提取的属性名.
     * @param separator
     *            分隔符.
     */
    public static String extractToString(final Collection collection, final String propertyName, final String separator) {
        List list = extractToList(collection, propertyName);
        return StringUtils.join(list, separator);
    }
}
